Preparing the Soil

The groundwork

Before any sowing or planting can start in the garden, the soil must be prepared by working it into a condition that will promote seed germination and support growing plants. Groundwork is also important for burying weeds and green manures, mixing in lime and fertilisers and incorporating animal manures and composts. However, cultivations should be kept to a minimum at all times, and must be done only when soil conditions are right.

Groundwork is important for burying weeds (left) and mixing in animal manures (right).

Soil preparation is typically done in two steps:

• Loosen the soil. Digging with a fork or spade is the simplest way of loosening the soil in smaller gardens. In its simplest form, digging is restricted to turning over the topsoil, normally to a depth of 25cm (about the blade length of a spade), though this should be less where the topsoil is thin. A more complicated two-staged operation, called 'double digging', can be employed to work the soil to a greater depth. The topsoil is first removed to a depth of 25cm – or less in gardens with thinner topsoils. The exposed soil underneath is then loosened with a fork and covered back over with the topsoil. Despite the extra labour, this double working is an effective antidote to hard pans and compaction, and gives the crop roots more depth from which to extract water and nutrients.

Digging the soil is the simplest way of loosening the soil.

• Smooth the surface of the soil and create a fine tilth. The dug-over soil will have an uneven surface, and some soils may be left with large clods on the surface. If the soil is dry the clods may be hard to break down, and spraying with water and waiting for a few hours will make the clods easier to break down. A rake or fork are the best tools for the job. Then the rake can be used to smooth out the surface and produce a fine-structured tilth that is suitable for sowing or transplanting.

Raking the soil produces a fine tilth suitable for sowing seed

Rather than hand digging and raking gardeners growing larger areas of vegetables may resort to the use of a rotavator. These machines can be a useful tool since they both loosen the soil and produce a fine tilth at the same time. They must, however, be used judiciously since over-cultivation can lead to a breakdown of soil structure and the formation of pans.

Rotavating loosens the soil and produces a fine tilth at the same time.

Bed time

One of the best ways of growing vegetables and herbs is in a bed system where crops are grown in pre-designated areas. These areas, or ‘beds’ can be laid out in squares, rectangles or any shape of the gardeners’ choosing. Foot traffic is confined to the pathways between the beds, ensuring there is no soil compaction where the vegetables are grown. The beds must be narrow enough so that their centres are only an arm’s length away, allowing the middles to be reached from the paths.

Beds can be either flat or raised. Flat beds are just like their name, while raised beds are built up by adding topsoil taken from the pathways. Raised beds can improve drainage of heavy soils, especially during winter in high rainfall areas. They often succumb to rainfall erosion, but can be made more permanent if they are enclosed inside wooden, plastic or brick edging.

Planting into a flat bed; rows of flat beds with black plastic as a mulch.

Raised beds: with no edging (right) and with a wooden edging (left).

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No-dig gardening

Practitioners of no-dig gardening forgo the tradition of turning the soil, preferring instead to mulch the surface with organic matter. Earthworms that thrive under the mulch replace the work done by spades and forks, dragging the organic matter into their tunnels and improving the soil’s fertility and structure.

Gardening tools, however, cannot be abandoned completely, and some soil disturbance in a no-dig garden is inevitable. Holes, for example, will need to be dug for transplanting, while root crops may need to be forked out of the ground. Compacted soils may also need to be loosened up before the no-dig technique can be adopted.

Container gardening

Would-be gardeners with access to only a balcony or patio can try growing their crops in containers. Possible containers come in various shapes, sizes and materials, from purpose-built terracotta or plastic pots available from garden centres, to huge plastic tubs sold by specialist suppliers. For the more ecologically-minded, discarded items such as bath tubs and sinks can be recycled as miniature gardens.

The choice of growing media is critical for success, and the use of a high quality propagating compost is essential. There is, though, less room for error in container gardening, and special attention must be given to keeping the containers well-watered and topped-up with nutrients throughout the growing season.

Container growing can be fun – vegetables can be grown in almost any container!